The present invention concerns concreting machines of the kind typically used for making cast items with cavities or corings in the shape of concrete blocks for erecting walls and elements, including a cellular bottom part with cells opening upwards as well as downwards which define the desired basic shape of the individual blocks and elements, and where the bottom part includes at least one core member placed in respective cells where the said cavities/corings in the mould are desired to be disposed, and a corresponding top part which have pressing pistons projecting downwards from an upper holding plate and formed with lower pressing plates that fit down into respective underlying cells in the bottom part and are thereby usable for downwards ejection of the cast items from the cells, and where the bottom part includes means ensuring that the core members keep their position in the bottom part.
The equipment is used in the way that the bottom part is placed on a casting board placed on a vibrating table with the top part in elevated position above the bottom part. A concrete supply car is guided along the upper side of the bottom part in the space below the top part for bringing concrete into the casting cells for filling up the latter with concrete. After finishing the filling, the supply car is pulled out, and the top part is lowered until the said pressing plates hit down on the concrete surfaces in the respective casting cells. Then the top part is utilised as a multi-pressure piston for consolidating the concrete mass in individual casting cells, which will occur under strong vibration of the moulding equipment in order to liberate air from the concrete mass. Hereby the concrete items are consolidated to the desired compact block shape and uniform thickness. Then the top part is retained in its top position in relation to the bottom part, and the bottom part is acted on by force for being lifted up from the casting board, whereby the cast items, which by the pressure maintained from the top part cannot participate in this elevation, will remain standing on the casting board during the stripping. When the stripping has ended by upwards displacing of the bottom part to a position, in which its underside is elevated to at least the level of the pressing plates of the top part, the semi-solid cast items can be removed from the vibrating table by pushing out therefrom after lifting the top part, after which a new casting cycle can be commenced subsequent to lowering the bottom part to the casting board and elevating the top part to its starting position.
In connection with casting concrete blocks with cavities, e.g. foundation blocks, perforated blocks and elements with cavities, there is used a moulding equipment including a bottom part with casting cells with pendant cores corresponding to the desired shape of the cavity/coring in the concrete block and a top part with pressing plates pendant from support bars and substantially corresponding to the shape of the casting cells, and so that the pressing plates by stripping the items by vertical displacement of the bottom part are passed down through the casting cells.
From DE-A-19 701 590 is known a traditional moulding equipment On a casting plate, e.g. placed on a vibrating table, a mould frame is secured. The mould frame is arranged with the desired number of partitionings in order thereby to cast a number of elements. After placing the partitionings in the mould, a number of cores are placed from above for providing corings in the finished elements. The cores are fastened in a core holding element which bear on and is fastened to the mould frame. The casting mass, typically concrete, is then placed in the mould, after which mould with casting mass are vibrated. After finishing consolidation, stripping is performed by the mould frame with the cellular insert being elevated, whereby the cores are drawn up by means of the core holder element, after which the cast elements remain on the casting plate.
Traditionally, core members have been welded to a support of a core iron, which in turn has been welded to the mould frame with the cells. Alternatively, the core members have been welded to a supporting yoke, a structure above the mould which has carried the core member by downwards projecting rods.
The drawback of the welded core member is that after the required hardening of the welded core member, welding is performed again on the support iron of the core member for fastening the core member in the mould frame itself. By welding the already hardened core member, stresses arise in connection with the welding, and these stresses may give rise to breakage later. Another drawback is that substitution of the core member when worn-out, is made difficult, since the welding is to be ground before the new core member can be welded in. Repeating this welding weakens the mould frame and depreciates its service life. The problem is particularly outspoken by core members that do not abut on or are in contact with one of the sides of the cells in the bottom part, and may thus not be fastened to the walls in the cells; in the following, these core members are designated ‘centre core members’.
By the invention, a bottom part including new means for securing said core members to remain in their position in the bottom part. These means may in a first embodiment be constituted by at least one top plate supported by and releasably fastened to the bottom part, and that the core members are fastened to the top plate, preferably by bolt connections.
The novel feature of the invention is that the core members forming part of the mould are fastened directly to the top plate, preferably by bolts. The above weldings are hereby avoided when mounting and exchanging the core members, which will imply weakening of the mould frame.
The core members that are bolted to the top plate typically include one or more intermediate pieces.
In cases where the top plate supports one or more centre core members, which are not in contact with the sides of a cell, the centre core member/members are carried, according to the invention, by through-going supports in the top plate which in turn is carried releasably fastened to the core members in contact with opposite cell sides and fastened in the cell sides, preferably also by bolt connections. Where these integrated supports run, the pressing plates of the top part are thus not coming into contact with the block items cast in the mould, making the surfaces of the item appear slightly uneven, but this has no practical significance as these surfaces on the end product are hidden.
In connection with this design of the top plate, the pressing plates in the top part are divided into several pieces.
If cast items of the kind already described, where all surfaces are smooth, are wanted to be produced, the design of the bottom part may alternatively be made so that the top plate on the centre core member/members is fastened to a supporting yoke which is supported and flexibly attached to the bottom part The supporting yoke substitutes the integrated centre core supports.
The difference of the core being bolted on the top plate or on the yoke is that if the core is bolted to the top plate, the pressing plates of the top part become divided so that they can come into contact with the concrete between the core irons supports integrated in the top plate. If, however, the cores are carried by a yoke, the pressing feet of the top part can be made in one piece corresponding to the top side of the product.
Another advantage of the invention is that the constituent core members may be built up from modules. These modules are hardened after the making. The modules are bolted together into core members which form the internal shape of the concrete block, and the core members are then bolted into the mould frame.
Furthermore, the use of bolts implies that the core members may rapidly and simply be exchanged in the mould frame. This may possibly occur simultaneously with the wear plates forming the external side of the concrete block are exchanged; these wear plates are also bolted to the mould frame.
By the invention is furthermore provided the possibility that the core member, whether bolted to the top plate or to the supporting yoke, may be flexibly bolted on by using a vibration dampening shim, which is preferably disposed between the intermediate pieces and the core members.
The said vibration dampening shim has the advantage that it is ensured that not all vibrations from the consolidation are transmitted to the core member support. By the slight flexibility inherent in the vibration dampening shim, it is simultaneously also achieved that the core can oscillate (vibrate) independently of the mould frame and thereby improve consolidation, resulting in that the surfaces of the cast items will appear more smooth. The vibration dampening shim implies that the core members can move slightly in relation to the mould frame, and that they can oscillate slightly differently from the mould frame, further ensuring that the core member/members are not subjected to quite so strong vibration during the consolidating vibration, thus safe-guarding the constituent core members.
As alternative to the ‘flexible’ bolting on of the core members attained by using the vibration dampening shim, the vibration dampening shim may be substituted by a compact spacer element, whereby the core members are rigidly connected to the mould frame.
On FIGS. 1 and 2 is shown moulding equipment 2 for a concreting machine. The bottom part 4 is shown lying on a casting board 28 on a not shown vibration table. The shown top part 14, cf. FIGS. 1 and 2, has a strong holding plate 16 to which is welded a number of downwards projecting support rods 18 that carry the pressing feet 20 bolted thereon, each having a contour corresponding to the top side shape of the concrete blocks 22 to be cast. The pressing feet 20 will thus together form a bottom plate broken by a pattern of slits between the pressing plates, and this pattern will correspond to the shape of the open cells 6 which appear in the associated bottom part 4 which thus display the mentioned casting cells 6 that are open both upwards and downwards.
The moulding equipment 2 shown in FIGS. 1 and 2 are shown with the top part 14 elevated above the mould bottom part 4, ready for filling casting material (concrete). After filling concrete into the cells 6 and vibration at the vibrating table (not shown) with the pressing feet 20 of the top part inserted in the cells 6 and in contact with the items 22, it is actual to strip the items 22, in practice by elevating the bottom part 4 with the top part 14 retained, whereby the pressing feet 20 will hold the items 22 down onto the casting board 28, as it appears from FIG. 7.
FIGS. 3 and 4 are perspective views of the core member structure for the first embodiment of a core support integrated in the top plate 10 according to the invention, and a second embodiment of a core support with structure as a yoke 12 according to the invention, respectively. Here, it appears that the two outermost semi-cores 9 are securely bolted together with the end gable 7 to the mould frame. The vibration dampening shim 24 is seen here, providing that the intermediate cores, which consist of two semi-cores 9 bolted together, have little flexibility in relation to the mould frame. This vibration dampening shim 24 may alternatively be substituted with a compact shim, whereby the core elements are entirely secured to the mould frame.
In FIGS. 5 and 6 are found a combined side and side sectional view of the core element structure for the first embodiment of a core support integrated in the top plate 10 according to the invention and a second embodiment of a core support structured as a yoke 12 according to the invention, respectively. These views also depict the vibration dampening shim 24.
In FIG. 7 is illustrated a newly cast item 22 right after stripping. At the stripping the newly cast items 22 remain standing on the casting board 28 when the bottom part 4 of the mould 2 is lifted. By this movement of the bottom part 4 relative to the top part 14, the pressing pistons 18 are kept in their position in relation to the cast item 22, so that the cast item 22 is pressed out of the bottom mould part 4 and thus remain standing on the casting board 28. The pressing feet 20 arranged at the underside of the top part 14 and/or the pressing pistons 18 thus press the pre-cast item out of the mould. This is further facilitated by the cores 8, 9 being designed with bevelling. By subsequently withdrawing the top part 14 with pressing pistons 18 and pressing feet 20 from the bottom part 4, the newly cast item 22 may then be transported out the machine on the casting board, and the bottom part 4 lowered down to a new casting board 28, after which the mould 2 is ready for a new casting cycle, possibly after applying release agent and/or mould oil.